CLINICAL-SIGNIFICANCE OF INTERLEUKIN-6 MEASUREMENT IN EARLY RHEUMATOID-ARTHRITIS - RELATION WITH LABORATORY AND CLINICAL-VARIABLES AND RADIOLOGICAL PROGRESSION IN A 3 YEAR PROSPECTIVE-STUDY

Objective-To evaluate the clinical significance of interleukin-6 (IL-6 ) measurements in relation to laboratory and clinical measures of dise ase activity and radiological progression in early rheumatoid arthriti s (RA). Methods-A Irrespective study was performed in 51 patients with early RA during the first three years of the disease, with monthly cl inical and laboratory assessments and biannual radiographs of the hand s and feet. IL-6 was measured by immunosorbent assay sectional (n = 51 ) and longitudinal (n = 20) correlations between plasma IL-6 concentra tions and values of C reactive protein (CRP), serum amyloid A protein (SAA), erythrocyte sedimentation rate (ESR), haemoglobin (Hb), platele ts, and joint scores were calculated, and correlations made between ti me integrated values of IL-6, CRP and ESR, and radiological progressio n over three years (n = 20). Results-Significant correlations were fou nd between IL-6 and the acute phase response and platelets, but variab le results were obtained for the correlation between IL-6 and Hb. In c ontrast to a significant correlation between time integrated values of CRP or ESR and radiological progression, time integrated values of IL -6 did not correlate with radiological progression over three years fo llow up. Conclusion-The course of disease activity and the radiologica l progression of joint damage are better reflected by CRP, SAA, and ES R values than by plasma IL-6 concentrations, particularly in stages of low disease activity.